Automatic button-clamp lifting means



Ju1 14,19s 3 MMcCANN 2,645,192

' AUTOMATIC BUTTON CLAMP LIFTING MEANS- Filed April 26, 1952 SSheets-Sheet l l mvz zvron A mic/lac! mcavm WITNESS BY Wza 4 wjmmdg ATTORNEY M. M CANN AUTOMATIC BUTTONwCLAMP LIFTING MEANS July 14, 1953 3 Sheets-Sheet 2 Filed April 26, 1952 INVENTOR.

' mic/we! )flcbme ATTORNEY M. MCCANN AUTOMATIC BUTTON-CLAMP LIFTING MEANS July 14, 1953 5 Sheets-Sheet 3 Filed April 26, 1952 j ZINIVHVTOR.

ATIWRNEY Patented July 14, 1953 uNiTEosrATEs PATENT orrics Michael McCann, Union, N. J., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application April 26, 1952, Serial No. 284,510

' 9 Claims. (01. 112-110) This invention relates to article attaching machines or other cyclically operated sewing machines, and more particularly; tosewing machines in which the article to beattached is gripped and supported by a clamping device during the stitching operation.

It is an object of this invention to provide an improved automatic means for shifting the article holding clamp into aninoperative open position at the completion'of the stitching cycle in order to facilitate removal and reloading of the work and to sever the thread between successive articles thus stitched. It is also an object to provide means for automatically repositioning said clamp at the start of the succeeding stitching cycle.

It is a further object to provide novel means for operating thread-controlling devices simultaneously with the automatic means for opening the clamp in order to prevent unthreading of the needle at the start of the succeeding cycle of operation and'to prevent the thread end from being pierced by the needle.

A still further object is to provide a simple and effective means for discontinuing the automatic clamp-lifting and thread-controlling operation at the will of the sewing machine operator.

The prior devices in which the article holding clamp is automatically opened at the completion of the stitching cycle have been found objectional for several reasons. In one type of construction, the motion required to open the clamp is obtained by means of an interconnection with the needle-bar during the final upstroke of the bar in the stitching cycle. The needle-bar and its bearings are ill-suited for such an unusually heavy load and the increased wear caused thereby is frequently detrimental to satisfactory operation of the machine. g In another type of construction, of which I am aware, the motion necessary to open'the clamp is obtained from a source in the sewing machine which is removed from the point at which the motion is applied to the clamp. This construction, therefore, necessitates a bulky and complicated mechanical linkage for transmitting the motion to the clamp. v

The present invention encompasses a construction which is compact and economical to manufacture and which derives the actuating motion by means of a novel interconnection with the machine actuating mechanism which is advantageously located substantially on the line along which the lifting force is applied to the 2 clamp. Moreover, the motion transmitting member of the present invention is structurally wellsuited for imparting the desired motion.

With the above and other objects and advantages in view as will hereinafter appear, the invention comprises the devices, combinations and arrangement of parts hereinafter described andillustrated in the accompanying drawings of a preferred embodiment in whichL Fig. l is a side elevational view taken substantially in a vertical section of a sewing machine embodying the subject matter of this invention.

Fig. 2 is a front end elevational view of the sewing machine of Fig. 1 with the cover-plate of the sewing head removed.

Fig. 3 is a sectional view of the sewing machine bracket arm taken substantially along the line 33 of Fig. 1 and including a fragmentary portion of the work-clamp structure.

Fig. 4 is a sectional view ofthe sewing machine taken substantially along the line 4-4 of Fig. 1.

Fig. 5 is a fragmentary sectional view taken substantially along line 55 of Fig. 1, with a portion of the lower pattern cam removed to clearly illustrate the stop motion mechanism.

Referring more particularly to the drawings, l0 indicates a supporting base for a single thread chain-stitch sewing machine adapted specifically for cyclic operation in attaching buttons and similar articles. The machine frame comprises a work-supporting bed I I, a vertical standard l2, and a bracket-arm 13 which overhangs the worksupporting arm and terminates in a sewing head M which is closed by a cover-plate I5. The machine frameis pivotally cradled on the support: ing base by means of spaced trunnions', of which one is indicated at [B in Fig. 1.

The stitch-forming instrumentalities comprise a needle ll carried by a needle-bar l8 endwise reciprocable in a needle-bar gate l9 which is pivoted for lateral jogging movement on a hollow rod 20 secured vertically in the bracket-arm. Cooperating with the needle in the formation of stitches is a rotary chain-stitch looper 21 carried by a looper-shaft 22. In order that the looper may be jogged laterally with the needle, the looper-shaft is journaled in a bracket 23 which is supported for lateral jogging movement beneath the work-supporting bed I I by means of a transverse slot 24 and fastening screw 25 and also a supporting bridge piece 28 which depends from the bed. r

I The actuating-mechanism of the machine for reciprocating the needle and rotating the looper comprises a main shaft 21 which is journaled in the bed. One endwise reciprocation is imparted to the needle-bar for each revolution of the main shaft 21 by means of an eccentric 28 fast on the main shaft. A pitman 29 embracing the eccentric is connected by means of a rock-arm 30 to one end of a needle-bar actuating rock-shaft 31 which is journaled in bearings 32 and 33 in the bracket arm I3. A lever 34 fast on the rock-shaft 3| adjacent the bearing 33 carries a pivotally mounted block 35 which rides in a horizontally arranged guide channel 36 formed in an abutment member 31 which is clamped to the needlebar as clearly illustrated in Fig. 1. With this driving connection, it will be understood that the timing and depth of penetration of the needlebar reciprocation will remain constant regardless of the lateral position of the needle-bar due to swinging of the gate [9.

The looper is rotated in timed relation with the needle reciprocation by means of a one-to-one spur gear connection 38 between the looper shaft 22 and the main drive shaft 21. In order to accommodate lateral jogging of the looper shaft, a universal connection indicated generally as 40 is provided between the looper shaft and the hub of one of the spur gears 38.

The mechanism will now be'described by which synchronized stitch-by-stitch lateral jogging movements are imparted to the needle-bar and the looper. Journaled vertically in bearings 4|-4I in the machine standard is a cam-shaft 42 which is driven at a speed less than that of the main drive-shaft by means of a worm 43 fast on the main drive-shaft and a worm-wheel 44 carried by the cam-shaft. A speed reduction of 15-1 is provided in the machine of the preferred embodiment, and since a stop motion device is provided which permits the machine to operate until one complete revolution of the cam-shaft has been completed, as will be described in detail hereinafter, a group of 15 stitches will be formed in each cycle of operation of the machine. Any other suitable speed reduction would be permissible depending upon the number of stitches desired in each cycle of operation. A pattern cam 45 fast on the upper extremity of the cam shaft 42 has a sinuous cam-groove 46 formed in its face. Tracking the cam-groove is a roller follower 41 carried by a follower lever 48. The follower lever is freely pivoted on a shouldered screw 49 threaded into the upper end of a vertically arranged rock-shaft 50 which is journaled in a bearing 5| depending from the bracket-arm, and a bearing 52 in the machine bed. An arouate undercut sector-slot 53 is formed in the follower lever 48 and embraces a slide-block which is carried by a link 55 pivotally secured by means of a stud 55 to an arm 51 of the needle-bar gate I8. A knurled thumb-nut 58 serves to clamp the slide-block in selected position along the sectorslot at any one of a range of distances from the fulcrum of the follower lever, which fulcrum is provided by the pivot screw 49, thus providing a means for regulating the amplitude of lateral jogging movement of the needle-bar.

A side cover-plate 59 is provided to enclose the mechanism in the standard and in the bracketarm. The side cover-plate is held in place by a shouldered thumb-nut 60 which is threaded on a rod 6| that extends outwardly from within the standard. The plate 59 is formed with an outwardly protruding portion 62 which accommodates the lever'58 and the-adjusting thumb-nut 58. A hinged cover 83 normally closes the top of the protruding portion 62 so that access may be conveniently had within the bracket-arm to the thumb-nut 58.

Lateral jogging movements are imparted to the looper by means of linkage connections between the needle-bar gate l5 and the looper-shaft carrying bracket '23. To this end a link 69 is journaled at one end on the stud 58 carried by the arm 51 0f the needle-bar gate and is pivotally connected at the other end to a rock-arm 10 fast on the vertical rock-shaft 50. Beneath the bed, a second rock-arm 1| is secured to rock-shaft 50, and is pivoted to one arm 12 of a lever 13. The lever 13 is fulcrumed on the fastening screw 25 which also serves to slidably support the looper carrying bracket 23. A second arm 14 of the lever 13 drivingly engages a slotted 111g 15 depending from the looper carrying bracket 23. The looper is oscillated laterally due to the action of the lever arm 14 but this oscillatory movement occurs about a vertical axis determined by the universal connection 40. The various elements of the driving linkage are proportioned so as to provide an equal amount of lateral movement of both the needle and the looper.

Fig. 5 best illustrates the stop-motion device by which the cyclic operation is controlled and the machine brought to rest at the completion of each rotation of the cam shaft 42. On the outboard extremity 'of the main drive-shaft is secured a driving-pulley 16 and a freely rotatable idler-pulley 11. An'endwise slidable bar 18 which is Journaled in the machine frame carries at its outer extremity a stop member 19 and an arm provided with a belt-shifting member 8|. The bar 18 is normally biased outwardly by a spring 82 to a position .as illustrated in Fig. 5 in which the :bel-t-shifting-member is disposed opposite the idler pulley and the stop member operatively engages a stop-cam 83 which is carried by the driving-pulley, thus locking the machine in a predetermined stopped position.

The bar 18 at its inner extremity is provided with a lug 84 that carries a depending pin 85 by which the bar '18may be shifted inwardly, as for instance, by any usual treadleor knee shift connection (not shown). The lug -84 isalso formed with a latch pin85 which cooperates with a latch lever 81 pivoted to the machine bed at 88 and is biased by a small spring 89 against the latch pin .86. When the 'bar 18 is-shifted inwardly, the latch lever overrides and engages the latch pin to maintain the bar in withdrawn position. The belt-shifting arm is disposed opposite the driving pulley in this position, and the stop member 19 is disposed at one side of the stop-cam. The machine, therefore, operates in normal fashion. In order that the machine may be stopped after one revolution .of the cam-shaft 42, a cam projection '80 is provided on the hub SI of wormgear 44 Cooperating with the cam projection is a follower-arm 92 carried'by the'latchlever. The cam projection is timed to trip the'latch lever and release the bar 118 at approximately one-half revolutionof the=main drive-.shaft in advance of the desired stopped position, such thatthe parts are shifted by spring'82 to the position as in Fig. 5 and the momentum of the actuatingmechanism carriesit into stopped position.

Associated with the stitch-forming instrumentalitiesis a'work-holding-clamp-of the typehavingopposedfabrimgripping jaws and a provision in one of the jaws-for positioning an'article to be attached to the fabric. The clamp disclosed in my prior -Patent No.-2, 200,929, "May 14, 1940, may

be used advantageously. with theflpresent invention. The clamp illustrated in the preferred embodiment differs slightly from'the patented construction. Referring in particularto Fig. I, the clamp comprises a base-plate 93 supported for sliding movement lengthwise of the bed- II by undercut guide. blocks 94. A fabric supporting the plate 95 is secured at the forward extremity of the base-plate 93 and forms the lower jaw of the work-clamp. Upstanding lugs 96-96 are provided at the rearward extremity of the base-plate and are formed to receive a hinge pin 91 on which is journaled a shank 98 which carries the upper jaw of the work-clamp indicated generally as 99. The upper jaw is of usual construction including three spaced button engaging fingers I00 biased toward a common control point by means of a leaf spring I0 I. The

upper jaw 99 is normally biased downwardly toward the lower jaw 95 by means of a spring (not shown) disposed within the hollow rod 20. Spring pressure, adjustable by means of the knurled screw I02, is transmitted to the clamp by a presser-bar I93 which bears against the shank 98 between two spaced confining members I04-I04 carried by the shank. By this construction, the presser-bar may accommodate sliding movement of the clamp lengthwise of the machine bed.

It will be understood that lateral jogging of the needle and looper is utilized to provide securing stitches between two holes of a button. Thus, in stitching two hole buttons, the work-holding clamp is not shifted and the shank 98 may, if desired, be pivoted to supporting lugs IDS-I05 carried by the machine standard. In stitching four hole buttons, however, the work-holding clamp must be shifted lengthwise of the bed to present the second pair of holes in the button to the stitch-forming instrumentalities after a predetermined number of stitches have been made between the first pair of holes.

The motion necessary to shift'the clamp between stitching of the first and second pair of holes in a fiat button is derived from a pattern cam I06 fast on the lower extremity of the vertical cam shaft 42. The pattern cam (see Fig.5) is formed with an endless groove having two substantially semicircular portions I01 and I08 each with a different radius. Tracking the groove is a roller-follower I09 carried by a follower-arm IIO which is fast on a stud-shaft III journaled vertically in the bed II. At its upper end, the stud shaft carries a slotted leverarm II2 which is arranged to transmit the desired longitudinal movement to the work-clamp in a manner as disclosed in detail in my above noted U. S. Patent No. 2,200,929. I

At the completion of the stitching cycle, upper jaw 99 of the button clamp must be lifted in order for the work to be removed and replaced. Since the button is then secured to the cloth by the stitches, the cloth is raised with the button and the last limb of needle thread retained by the looper is broken beneath the cloth in a manner well known in the art, thereby freeing the'work for ready removal. According to the present invention, the button clamp may be opened either manually as by a foot treadle, knee shifter, or the like, or automatically by an interconnection with the operating mechanism of the sewing machine.

Journaled in bearings I2 I-I2I in the bracketarm is a clamp-lifting rock-shaft I22 which is arranged parallel to the needle-bar actuating rock-shaft 3I. As shown clearly in Fig. 4, an actuating lever I23 fast on the rock-shaft I22 extends rearwardlyof the machine frame and is pivoted at its free extremity to a depending push-rod I24. A coil spring I25 is arranged on the rod I24 in compression between the machine frame and a collar I26, thus urging the clamplifting rock-shaft into a position in which the clamp is lowered. Also connected to the collar I26 is a chain I2! which is, in turn, connected to a foot treadle (not shown), or the like,:by which the clamp may be lifted manually. ,The rockshaft I22 is provided with connections for lifting the upper jaw 99 of the work-clamp. These connections comprise a rock-arm I28 which is securedto the rock-shaft I22 at a point beyond bearing I2I' in the bracket-arm. The rock-arm I28 is apertured at its free end to loosely accom: modate a tranversely arranged bolt I29 having a flattened head I30 and being provided with a flattened nut I3I at the opposite side of the rockarm. Passing through the nut I3I is a rod I32 which is pivotally secured at its lower extremity to a lug I33 formed to extend from the presserfoot confining members I04--I04 carried by the work-clamp shank 98. The rod I32 is threaded at its upper extremity and provided with a thumb-nut I34 by which the rod andthe buttonclamp are lifted when the rock-shaft I22 is oscillated. Passing through the head I39 of the transverse bolt is a rod I35 which is pivoted at its lower extremity to a rock-arm I36 which actuates a thread-wiper. The thread-wiper is clearly H1113?- trated in Figs. .1 and 2 and comprises a spring wire thread-engaging member I31 which is secured to a lever-arm I38 fast .on a short rock'- shaft I39 which is journaled in a bracket I40 depending from the head of the sewing machine. The actuating rod I35 for the thread-wiper is provided with collars MI and I42, one on each side of the flattened head I30. By means of the upper collar I4I, the thread-wiper is turned positively in a counterclockwise direction as viewed in Fig. 2 to a position at the right of the needle when the button clamp is lifted. The thread wiper during this movementengages and pulls the severed end of the needle thread out of the Work. When the button-clamp is lowered, the thread-wiper is returned positively in a clockwise direction by means of a collar I42 to a position to the left of the needle. During thisreturn movement of the thread-wiper, the thread is carried'with it to a position out of the line of action of the needle at the start of the succeeding stitching cycle. Also secured to the clamp-lifting rock-shaft I22 is a thread pull-off arm I43 arranged between the usual thread-nipper I44 and the thread-tensions I45, I46 when the clamp is lifted, the arm I43 cooperates with the stationary thread-guide M1 in the usual manner to draw sufficient slack thread through the tensions I45, I to provide for the initial stitch of the succeeding cycle.

Automatic'lifting of the button-clamp is effected inthe present invention by means of an actuating lever I50 which is secured forioscilla tion with the needle-bar actuating rock-shaft 3I at the opposite side of the rock-shaft bearing 33 from the needle-bar actuating lever 34. The clamp-lifting rock-shaft I22 is shiftable endwise in its bearings I2I-I2I. When the rock-shaft I22 is shifted to a left hand position as illustrated in Figs. 1 and 4, the clamp-lifting rockarm I28 overlies the actuating lever I50=and is lifted thereby on the upstroke of the needle, as best illustrated in Fig. 3. When the presser lifting rock-shaft I22- is shifted to the rightythe' rock-arm I28 will be disposed completely to .one side of the path of the actuating lever I50 and consequently will be uneffected thereby. Rockarm I28, therefore, in the present embodiment serves a double function; first, as rock-arm by which oscillation of the rock-shaft is transmitted. to the clamp and to the thread-wiper, and second, as an element cooperating with the lifting lever I50 to provide a separable driving connection between the needle-bar actuating shaft 3I and the clamp lifting rock-shaft I22. It will be appreciated that a separate rock-arm may be provided for each of these functions; however, the construction of the preferred embodiment provides an economical, compact and efiicient arrangement.

The rock-arm I28 is normally biased laterally out of engagement with the lever I50 by a coil spring II which is arranged on the rock-shaft I22 between the bearing I2! and a collar I52 fast on the shaft. In order that the button-clamp may be shifted automatically into raised position when the machine is stopped at the completion of each cycle, a cam member I53 is secured on the under side of pattern cam 45 for limited angular adjustment thereon by means of a slot I54 and a fastening screw I55. Cooperating with cam member I53 is a follower-arm I56 fast on a rock-shaft I51 which is journaled vertically in the bracket-arm. Also fast on the rock-shaft I51 is a rock-arm I58 which is apertured as at I59 to loosely embrace the clamp lifting rock'- shaft I22. The cam member I53 is adjusted in timed relation with the stop motion tripping cam lug 90 such that the follower arm I56 is engaged and shifted by the cam member I53 at the beginning of the final upstroke of the needle. A coil spring I60 arranged on the rock-shaft I22 between the collar I52 and the rock-arm I58 serves to transmit motion from the rock-arm I53 to the rock-shaftI22. Only a portion of the movement of rock-arm I58 will be transmitted into endwise movement of rock-shaft I22, the remainder will be lost in the compression of coil springs I5I and I60. The stiffness, i. e. modulus of elasticity, of spring I5I is made considerably greater than that of spring I60 so that normally a relatively large proportion of the movement of the rook-arm I58 is transmitted to the rock-shaft I22. The rockshaft I51 together with rock-arms I56 and I58 which are fast thereon, provides in effect a. bellcrank lever of which the arms I56 and I58 are offset one from the other along the turning axis of the bell-crank as is determined by the rockshaft I51.

The arrangement of opposed coil springs I5I and I60 provides means for effecting a throw-out of the automatic clamp-lifting mechanism without the necessity of disconnecting any of the mechanical parts. The automatic clamp-lifting mechanism may be rendered inoperative by means of a throw out plunger I6I which is arranged to enter an axial bore I62 formed in the head end of the clamp lifting rock-shaft I22. The plunger is formed with an enlarged knurled portion I63 which extends through an aperture I64 in the sewing head cover plate I5. The enlarged portion of the plunger is provided with a shouldered portion I65 which is adapted to bear against a counterbored seat I66 in the cover-plate I5 to prevent complete removal of the plunger from within the sewing head. The enlarged portion I63 is also provided with a transverse pin I61 which is adapted to enter the cover-plate and engage the inner surface thereof to lock the plunger in a depressed position. When locked in depressedposition, the plunger I 6| engages the bottom .of the bore I62 and provides a positive stop which limits the endwise movement of the rockshaft I22 in the direction of the sewing head. With the throw-out plunger in depressed position, it will be appreciated that all of the movement of the rock-arm I58 in response to actuation by cam member I53 will be assumed by compression of coil spring I60, the clamp-lifting rockarm I28 will then remain out of the path of movement of the actuating lever I50 and the machine will proceed to stopped position with the button clamp in lowered position. The clamp must then be lifted by means of the manual connection hereinbefore described.

Having thus set forth the nature of the invention, what I'claim herein is:

1. In a cyclically operated article attaching sewing machine including an endwise reciprocable needle-bar, a needle-bar actuating shaft, a workclamp for positioning an article with respect to said needle-bar, and a stop-motion device, means automatically opening said work-clamp at the completion of each cycle of machine operation, said means comprising, a work-clamp opening rock-shaft, complemental driving members carried for turning movement one on said needle-bar actuating shaft and the other on said rock-shaft, a cam-shaft, a first cam-means carried by said cam-shaft and effective to render said stop-motion device operative after a predetermined number of stitches, and a second cam-means carried by said cam-shaft, said second cam-means being effective upon operation of said stop-motion device to shift said complemental driving members into operative relation.

2. In a cyclically operated article attaching sewing machine including an endwise reciprocable needle-bar, a needle-bar actuating shaft, a workclamp for positioning an article with respect to said needle-bar, and a stop-motion device, means automatically opening said work-clamp at the completion of each cycle of machine operation, said means comprising an endwise shiftable workclamp opening rock-shaft, complemental driving members one fast on said needle-bar actuating shaft and the other fast On said rock-shaft, and means effective upon operation of said stop-motion device to shift said rock-shaft into a position of driving relationship between said complemental driving members.

3. In a cyclically operated article attaching sewing machine including an endwise reciprocatory n edle-bar, a needle-bar actuating shaft, a work-clamp for positioning an article with respect to said needle-bar, and a stop-motion device, means automatically opening said workclamp at the completion of each cycle of machine operation, said means comprising a work-clamp opening rock-shaft arranged parallel to said needle-bar actuating shaft, complemental driving members carried for turning movement one on each of said shafts, and means effective upon operation of said stop-motion device to shift one of said complemental driving members along its respective shaft axis into driving relationship with the other of said members.

4. In a cyclically operated article attaching sewing machine including an endwise reciprocatory needle-bar, actuating mechanism therefor including a needle-bar actuating rock-shaft, a work-clamp, a clamp opening rock-shaft arranged substantially parallel with said needlebar actuating rock-shaft, a pair of rock-arms one 9 secured to each of said rock-shafts, spring means normally biasing said clamp opening rock-shaft endwise to separate said rock-arms, and means effective after a predetermined number of stitches to superimpose said rock-arms in driving relation, said means comprising a cam driven by said actuating mechanism and arranged to shift positioning an article on said base with respect to said path of needle-bar reciprocation, a bearing formed insaid overhanging bracket-arm, a,

needle-bar actuating shaft journaled in said bearing, a needle-bar actuating lever carried by said shaft at one side of said bearing, a clamplifting lever carried by said shaft at the opposite side of said bearing, and mechanism arranged to transmit movements of said clamp-lifting lever to said clamp, said mechanism including a clamp lifting rock shaft journaled in said bracket-arm substantially parallel with said needle-bar actuating shaft, a driven member carried by said rock-shaft complemental to. said clamp-lifting lever, spring means normally biasing said driven member out of engagement to one side of said clamp-lifting lever, and cam means effective after a predetermined number of stitches to shift said rock-shaft endwise t0 position said driven member into operative interengagement with said clamp-lifting lever.

6. In a cyclically operated. sewing machine, a needle, a needle-actuating shaft, an oscillatory needle thread wiper, a work-gripping clamp, mechanism automatically opening said workgripping clamp and simultaneously oscillating said thread wiper, said mechanism including a rock-shaft having an axis disposed substantially parallel to the axis of said needle-bar actuating shaft, a linkage connection between said rockshaft and said work-gripping clamp, a linkage connection between said rock-shaft and said thread wiper, a separable driving connection between said shafts comprising adriving member carried for turning movement with said needlebar actuating shaft, a driven member carried for turning movement with said rock-shaft, and mechanism associated with said sewing machine effective after a predetermined number of stitches have been formed to shift at least one of the members of said separable connection along its respective shaft axis into operative interrelation with the other of said members.

7. In a cyclically operated sewing machin having a frame including a work-support and a bracket-arm overhanging said work-support, the combination comprising an endwise reciprocatory needle-bar, actuating mechanism including a needle-bar actuating shaft, a work-clamp, an article gripping jaw pivotally supported thereon, a thread-wiping device supported beneath said bracket-arm and having a flexible thread-engaging arm disposed for turning movement transversely of the path of needle bar reciprocation, mechanism for simultaneously lifting the article gripping jaw of said work-clamp and turning said thread-wiper, said mechanism comprising a rock-shaft journaled in said bracket-arm, a rock- :arm secured to said rock-shaft, a first connection element arranged between said rock-arm and 10 said article gripping jaw, and a second connection element arranged between said rock-arm and said thread-wiping device, and means automatically actuating said rock-shaft, said means including, a driving lever fast on said needle-bar actuating shaft, a, driven lever fast on said rockshaft, spring means normally biasing said rockshaft endwise to separate said levers, and mechanism driven by said sewing machine actuating mechanism effective at the completion of each stitching cycle to shift said rock-shaft endwise in opposition to said spring means.

8. In a cyclically operated sewing machine having a frame including a work-supporting base and a bracket-arm overhanging said base, a needle-bar, actuating mechanism therefor including a needle-bar actuating shaft journaled in said bracket-arm, a work-clamp, clamp-opening mechanism including a rock-shaft journaled in said bracket-arm, :a rock-arm carried by said shaft, and operative connections between said rock-arm and said work-clamp, a separable driving connection between said needle-bar actuating shaft and said rock-shaft effective to open said clamp automatically, a spring means arranged between said bracket-arm and said rockshaft and normally biasing said rock-shaft endwise to an extreme position in which said driving connection is separated and inoperative tolift said clamp, means automatically shifting said inoperative, said throw-out device comprising a rigid stop member shiftably supported for movement to a position betweensaid rock-shaft and said bracket-arm to lock said rock-shaft in said normal extreme endwise position.

9. Ina cylically operated sewing machine, a needle-bar supported for endwise reciprocatory movement in a vertical path, actuating mechanism therefor including a horizontally disposed needle-bar actuating shaft, a work-clamp normally biased downwardly into operative workgripping relation, clamp-lifting mechanism including a horizontally disposed endwise shiftable rock-shaft, a rock-arm secured thereto, and a connection element pivotally secured between said rook-arm and said work-clamp,-automatic clamp-lifting mechanism comprising a clamplifting lever secured to said needle-bar actuating shaft, and means for shifting said rock-shaft endwise to position said rock-arm in the path of said clamp-lifting lever after a predetermined number of stitches, said means comprising a cam driven by said actuating mechanism, a bell crank lever pivotally supported on an axis perpendicular to said clamp-lifting rock-shaft, said'bellcrank lever having a first arm disposed to follow said cam and-a second arm and operative connections between said second arm and. said rockshaft. c

MICHAEL McCANN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date McCann Feb. 6, 1951 Lyons Nov. 13, 1928 

